1. Field of the Invention
This invention relates to laminated composites including both fluoroplastic and non-fluoroplastic components bonded together by means of a melt bondable fluoropolymer adhesive, and is concerned in particular with a means for more efficiently applying and effectively utilizing the adhesive.
2. Description of the Prior Act
Melt-bondable fluoroplastic adhesives are well known, and widely utilized in the lamination of various components, including both fluoroplastics and non-fluoroplastics. Typical examples of such adhesives include perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP).
Conventionally, as a preliminary step in the lamination process, such adhesives are either integrally applied as coatings to one or both of the components being laminated, or films of the adhesives are interposed between the components. The materials are then subjected to elevated temperatures and pressures, thus causing the adhesive to melt and effect a bond at the interface between the associated components. When applying adhesive coatings to woven fabrics and/or porous components such as fiberglass mats, the adhesive coatings tend to penetrate into fabric interstices and surface voids. Thus, much of the adhesive migrates away from the bond interface and is therefore ineffective in creating adhesion during lamination. Since melt-bondable adhesives are some of the more expensive components of most laminates, this inefficient material utilization unnecessarily increases costs. Woven fabric flexibility can also be seriously compromised by interfiber adhesion resulting from penetration of the adhesive into fabric interstices and voids.
Films also exhibit a tendency to migrate away from bond interfaces. Also, minimum film thicknesses are dictated, in large part, by handling requirements as opposed to efficient adhesive utilization. Here again, therefore, excessive adhesive material is employed, with concomitant disadvantageous increases in product costs.
A primary objective of the present invention is to improve the manner in which melt bondable fluoropolymer adhesives are delivered to, and positioned at, the bond interface between components being laminated together.
A companion objective of the present invention is to minimize the amount of melt bondable adhesive required to effect lamination between components, at least one of which is a non-fluoropolymer.